This invention generally relates to semiconductor structures and to a method for their fabrication. More particularly, this invention relates to facilitating layer-by-layer monocrystalline material growth in composite semiconductor structures.
As is well known in the art, many semiconductor devices and integrated circuits are fabricated on silicon, at least in part because of the availability of inexpensive, high-quality, monocrystalline silicon substrates. Other semiconductor devices and integrated circuits are fabricated on other materials, such as gallium arsenide (GaAs), at least in part because of their superior electron transport properties. However, GaAs substrates are significantly more expensive than silicon substrates.
Even though GaAs substrates are more expensive than silicon substrates, these substrates are used for many applications because of their desirable characteristics. On the other hand, for other applications, other semiconductors such as silicon may be desired. It would be most preferable to have a single structure that is formed from a composite of silicon substrate and GaAs, or other compound semiconductor in order to integrate applications that are more appropriately formed on silicon with applications that are more appropriately formed on GaAs or other compound semiconductors.
Accordingly, a need exists for a semiconductor structure that provides both a high quality monocrystalline compound semiconductor portion and a high quality monocrystalline silicon portion, and for a process for making such a structure.